Conventionally, a travel control device that is installed in a vehicle and controls a travel of the vehicle is known. For example, Patent Literature 1 discloses a travel control device of a hybrid vehicle that selects, depending on driving conditions, whether travelling with a driving force for running only by a motor, or travelling with a driving force for running at least by an engine in the hybrid vehicle including the motor and the engine as driving sources of the vehicle.
The conventionally used travel control device of a hybrid vehicle described, for example, in the above-described Patent Literature 1 determines whether a state of charge (hereinafter referred to as SOC) of a battery (also referred to as secondary battery) providing electric power to a motor is a state below a first predetermined value, which is determined in advance, or a state of high load, for example, during high speed running or uphill running, which requires relatively high torque. The travel control device selects to travel with a driving force for running at least by an engine if it is determined to be one of the cases: the SOC is in a state below the first predetermined value, which is determined in advance; and a state of high load, for example, during high speed running or uphill running, which requires relatively high torque. Also, the travel control device selects to travel with a driving force for running only by a motor if it is determined not to be any of the cases: the SOC is in a state below the first predetermined value, which is determined in advance; and a state of high load, for example, in high speed running or uphill running, which requires relatively high torque.